1. Field of the Invention
The present invention relates to a method of correcting the attitude of an article being conveyed, and more particularly to a method of correcting the attitude of an article being conveyed which is transferred from a first feed path to two second feed paths.
2. Description of the Relevant Art
There is known a glass sheet shaping system for pressing a glass sheet to shape. In such a system, the glass sheet is heated to a temperature near its softening point by a heating furnace, and then conveyed along a feed path to pressing molds, which then press the glass sheet to shape. After the glass sheet has been shaped, it is delivered from the pressing molds to a suitable position such as for loading the glass sheet to a pallet.
It is customary to press a pair of mutually symmetrical glass sheets such as automotive side window glass sheets simultaneously with mutually symmetrical pressing molds. The pair of glass sheets is delivered from a heating furnace by a common first feed path to two second feed paths for the pressing molds. The first feed path comprises, for example, a plurality of rotatable rollers which can rotate at a prescribed speed. Where the pressing molds are annular ring molds disposed horizontally for pressing the peripheral edge of a glass sheet, each of the second feed paths comprises rotatable rollers positioned vertically movably in the ring mold and rotatable at the same speed as the above prescribed speed. The speed of rotation of the rotatable rollers of the first and second feed paths starts being reduced at a time upon elapse of a given period of time after one of the glass sheets has passed a certain position in the first feed path. At such a time, more than half of the glass sheets overlap the lower mold members of the respective lower ring molds. The rotatable rollers of the second feed paths are lowered before their speed is lowered to zero, so that the glass sheets are left on the respective lower ring mold members in registry therewith which serve as target positions. Then, the glass sheets are pressed by downward movement of the upper mold members of the respective ring molds. Subsequently, the glass sheets are delivered from the pressing molds to the loading position or other desired position. The speed at which the glass sheets are delivered by the first and second feed paths is controlled by a control unit.
When the paired glass sheets as they are heated in the heating furnace may be brought out of synchronism in the feeding direction when they are fed out of the heating furnace. More specifically, one of the glass sheet may be shifted back and forth with respect to the other glass sheet that serves to provide a reference position. The glass sheets may be thus shifted relative to each other for the reason that they are required to travel a relatively long distance through the heating furnace. More specifically, the pair of glass sheets is fed along by rotating rollers in the heating furnace. The longer the heating furnace, the greater the amount the glass sheets are shifted due to mechanical factors such as friction of the rotating rollers. Where the amount of shift of the glass sheets is large, the glass sheets may not be simultaneously transferred from the first feed path to the second feed paths. As a result, the glass sheets may not be simultaneously placed on the lower ring mold members in registry therewith in the normal control sequence of the speed control unit.
The above problem may also be caused when a wide article is fed over a first feed path in a direction normal to the width of the article and then transferred from the first feed path to two second feed paths.
The present invention has been made in an effort to correct the attitude of an article such as a glass sheet being conveyed through a system such as a glass sheet shaping system.